Introduction.— Entanglement is a form of quantum correlations that constitutes an essential resource for a number of quantum information tasks [1]}. Formally, it is defined as the impossibility of expressing the state of a composite system as the (convex combination of) product of subsystems' states. While this formal definition captures an essential difference between classical and quantum systems, deciding whether a given experimental quantum system exhibits entanglement is not an easy task. Nevertheless, a method for entanglement detection that is often successful employs entanglement witnesses [2]}, [3]}. These are observables represented by Hermitian operators \(W\)  such that \(\text{Tr}[W\sigma ]\ge 0\)  for all separable states \(\sigma \) . Therefore, observing \(\text{Tr}[W\rho ]< 0\)  implies that \(\rho \)  is entangled.
